Published on August 29, 2013 at 8:00 / Updated on April 16, 2020 at 15:31

Seasonal depression, also known as seasonal affective disorder, is a type of depression that affects 2 to 3% of Canadians. Symptoms tend to appear in the fall and winter, particularly in November, December and January. Seasonal depression is more common in areas that are further removed from the equator, where one's exposure to sunlight during the winter months is reduced.


Seasonal depression is believed to be caused by a decrease in a person's exposure to sunlight in winter, which can lead to changes in certain hormone or neurotransmitter levels (melanin, serotonin, etc.). It is thought that this hormonal imbalance is behind seasonal affective disorder.

Persons most at risk

Women are more likely to suffer from seasonal depression. In fact, three times more women have this disorder. Younger adults between 20 and 30 years old would be most affected by seasonal depression, but it should be noted that it can also affect children.


Symptoms appear in the month of October and disappear in April. There should be no symptoms throughout the summer months. The most common signs of seasonal depression are:

  • Inability to concentrate
  • Uncontrollable desire to eat sweets and weight gain
  • Fatigue and lack of energy
  • Sadness


Depression is diagnosed by a physician who will evaluate the symptoms (description, start, end, etc.). It may be difficult to differentiate seasonal depression from standard depression. But with the years, the diagnosis will be more precise.


Phototherapy (light therapy) is the most common treatment. The principle behind this treatment is to replicate the effects of sunlight through daily exposure to artificial light. Treatments are administered by a device or light box that provides exposure to a specific type of light (at a minimum of 10,000 Lux), 30 minutes a day, preferably in the morning.

In more severe cases, antidepressants can be prescribed to reduce the symptoms of seasonal depression if they are difficult to manage by the patient.

Vitamin D supplements also seem to help fight the effects of seasonal affective disorder.


Different means are used to prevent seasonal depression. Firstly, spending about an hour a day outdoors increases one's exposure to sunlight. In addition to improving our well-being, exercising outside also increases our exposure to natural sunlight. Furthermore, people with seasonal depression can make a few changes in their homes to increase the amount of sunlight. Reorganizing your work environment so you can work near a window, not having the curtains drawn during the day, painting the walls in a light colour and adding mirrors close to windows where lighting is not sufficient in certain rooms, are sound preventive measures. Taking a trip to a warm and sunny destination can also help...

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